Method for detecting flukicidal activity

ABSTRACT

This invention relates to a method for detecting the flukicidal activity of a compound or compounds comprising feeding a portion of liver tissue of an animal treated with the compound or compounds to a free-living flatworm and observing the flatworm for mortality or morbidity.

This is a divisional of application Ser. No. 08/306,072 filed on Sep.14, 1994, which is a divisional of Ser. No. 07/842,283 filed on Feb. 26,1992, now U.S. Pat. No. 5,371,239, which is a continuation-in-part ofSer. No. 07/455,685 filed on Dec. 22, 1989, now abandoned.

BACKGROUND OF THE INVENTION

It is an object of this invention to provide a method for treating,controlling, preventing and protecting warm-blooded animals frominfestation by helminths, acarids and arthropod endo- and ectoparasites,by administering thereto a nitropyrrole or pyrrole carbonitrilecompound.

It is also an object of this invention to provide a prophylactictreatment for farm and companion animals including cattle, sheep, swine,horses, poultry, fish, rabbits, goats, dogs, cats and the like toprevent the development of helminthiasis in said animals.

These and other objects will become more apparent from the detaileddescription of the invention set forth below.

SUMMARY OF THE INVENTION

The present invention relates to methods and compositions for treating,controlling, preventing and protecting warm-blooded animals againstinfestation and infection by helminths, acarids and arthropod endo- andectoparasites, by orally or parenterally administering or applying tosaid animals an anthelmintically, acaricidally or parasiticidallyeffective amount of a nitropyrrole or pyrrole carbonitrile compound.

DETAILED DESCRIPTION OF THE INVENTION

Nitropyrrole or pyrrole carbonitrile compounds useful in the presentinvention include those described in the following U.S. patentapplications which are incorporated herein by reference: U.S. patentapplication Ser. No. 07/795,407, filed Nov. 20, 1991, now U.S. Pat. No.5,204,332 which is a continuation-in-part of copending U.S. patentapplication Ser. No. 07/776,967, filed Oct. 15, 1991, now U.S. Pat. No.5,162,308 which is a continuation of U.S. patent application Ser. No.07/430,601, filed Nov. 6, 1989, now abandoned, which is acontinuation-in-part of U.S. application Ser. No. 07/279,909, filed onDec. 5, 1988, now abandoned.

A nitropyrrole or pyrrole carbonitrile compound suitable for the presentinvention has the following structure: ##STR1## wherein

W is CN or NO₂ ;

X is CN, Br, Cl, I or CF₃ ;

Y is H, Br, Cl, I or CF₃ ;

Z is H, Br, Cl or I; and

B is ##STR2## hydrogen, C₁ -C₆ alkyl optionally substituted with one tothree halogen atoms,

one tri(C₁ -C₄ alkyl)silyl,

one hydroxy,

one cyano,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms,

one C₁ -C₄ alkylthio,

one phenyl optionally substituted with one to three halogen atoms, oneto three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxy groups,

one phenoxy group optionally substituted with one to three halogenatoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxygroups,

one benzyloxy group optionally substituted on the phenyl ring with oneto three halogen atoms, one to three C₁ -C₄ alkyl groups or one to threeC₁ -C₄ alkoxy groups,

one C₁ -C₆ alkylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one C₂ -C₆ alkenylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one phenylcarbonyloxy group optionally substituted with one to threehalogen atoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄alkoxy groups,

one phenylcarbonyl group optionally substituted with one to threehalogen atoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄alkoxy groups,

one C₁ -C₆ alkoxycarbonyl group optionally substituted with one to threehalogen atoms or one to three C₁ -C₄ alkoxy groups,

one benzyloxycarbonyl group optionally substituted on the phenyl ringwith one to three halogen atoms, one to three C₁ -C₄ alkyl groups or oneto three C₁ -C₄ alkoxy groups, or

one C₁ -C₆ alkyloxycarbonyloxy group optionally substituted with one tothree halogen atoms,

C₃ -C₆ alkenyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ alkynyl optionally substituted with one to three halogen atoms orone phenyl group,

C₁ -C₆ alkyl substituted with one to three halogen atoms and one C₁ -C₄alkoxygroup,

C₃ -C₆ 1,2-alkadienyl, or

cyano;

R is C₁ -C₆ alkyl optionally substituted with one to three halogenatoms,

one hydroxy,

one cyano,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms,

one C₁ -C₄ alkylthio,

one phenyl optionally substituted with one to three halogen atoms, oneto three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxy groups,

one phenoxy group optionally substituted with one to three halogenatoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxygroups,

one benzyloxy group optionally substituted on the phenyl ring with oneto three halogen atoms, one to three C₁ -C₄ alkyl groups or one to threeC₁ -C₄ alkoxy groups,

one C₁ -C₆ alkylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one C₂ -C₆ alkenylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one phenylcarbonyloxy group optionally substituted with one to threehalogen atoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄alkoxy groups,

one C₁ -C₆ alkoxycarbonyl group optionally substituted with one to threehalogen atoms or one to three C₁ -C₄ alkoxy groups, or

one benzyloxycarbonyl group optionally substituted on the phenyl ringwith one to three halogen atoms, one to three C₁ -C₄ alkyl groups or oneto three C₁ -C₄ alkoxy groups,

C₃ -C₆ alkenyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ alkynyl optionally substituted with one to three halogen atoms orone phenyl group,

phenyl optionally substituted with one to three halogen atoms, one ortwo C₁ -C₄ alkyl groups, one or two C₁ -C₄ alkoxy groups, CF₃, CN, NO₂,di(C₁ -C₄ alkyl)amino or C₁ -C₄ alkanoylamino,

phenoxy optionally substituted with one to three halogen atoms, one ortwo C₁ -C₄ alkyl groups, one or two C₁ -C₄ alkoxy groups, CF₃, CN orNO₂, di(C₁ -C₄ alkoxyl)amino or C₁ -C₄ alkanoylamino,

C₁ -C₆ alkoxy optionally substituted with one to three halogen atoms,

C₂ -C₆ alkenyloxy optionally substituted with one to three halogenatoms,

di(C₁ -C₄ alkyl)amino,

N-(C₁ -C₄ alkyl)-N-phenylamino or N-(C₁ -C₄ alkyl)-N-halophenylamino, or

C₃ -C₆ polymethyleneimino.

The methods and compositions of the above invention are advantageousbecause they control and prevent helminth, acarid and arthropod endo-and ectoparasitic infestations and infections in warm-blooded animals,including cattle, sheep, swine, horses, poultry, fish, rabbits, goats,dogs, cats as well as humans.

Helminthiases is a widespread disease found in many farm and companionanimals and is responsible for significant economic losses throughoutthe world. Among the helminths causing significant damage are themembers of the class Trematoda, commonly known as flukes or flatworms,especially members of the genera Fasciola, Fascioloides, Paramphistomum,Dicrocoelium, Eurytrema, Ophisthorchis, Fasciolopsis, Echinostoma andParagonimus. It has been found that the present invention is uniquelyeffective against trematodes and provides superior control of theeconomically important Faciola hepatica, commonly known as liver fluke.

For control of fluke infections and infestations the pyrrolecarbonitrile compounds of formula I' are preferred: ##STR3## wherein Xis CN, Br, Cl, I or CF₃ ;

Y is H, Br, Cl, I or CF₃ ;

Z is H, Br, Cl or I; and

B is ##STR4## hydrogen, C₁ -C₆ alkyl optionally substituted with one tothree halogen atoms,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms,

one phenyl optionally substituted with one to three halogen atoms, oneto three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxy groups,

one C₁ -C₆ alkylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one phenylcarbonyl group optionally substituted with one to threehalogen atoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄alkoxy groups, or

one C₁ -C₆ alkoxycarbonyloxy group optionally substituted with one tothree halogen atoms, or

C₁ -C₆ alkyl substituted with one to three halogen atoms and one C₁ -C₄alkoxy group;

R is phenyl optionally substituted with one to three halogen atoms, oneor two C₁ -C₄ alkyl groups, one or two C₁ -C₄ alkoxy groups, CF₃, CN,NO₂, di(C₁ -C₄ alkyl)amino or C₁ -C₄ alkanoylamino,

C₁ -C₆ alkoxy optionally substituted with one to three halogen atoms, or

C₂ -C₆ alkenyloxy optionally substituted with one to three halogenatoms.

It has further been found that flukicidal activity, including thatexhibited by the above compounds, can be detected by an in vitroscreening method utilizing free-living flatworms, preferably the freshwater planaria Dugesia tigrina and Phagocata morgani.

This screening method provides a unique and efficient in vitro means todetect the flukicidal activity of a broad spectrum of experimentalcompounds where costly and inefficient invivo means have been requiredin the past.

In the screening method of the present invention, a non-lethal dosage ofa compound to be tested for flukicidal activity is administered to awarm-blooded animal, preferably a gerbil, by feeding in the diet, orallyby gavage, or parenterally. The non-lethal dosage for a given compoundcan be determined empirically or in accordance with the practices in theart for compounds of related type, The amount of the dosage also dependsupon the method of administration.

After administration of the compound a period of time is allowed to passfor circulation of the compound to the animal's tissue. The amount oftime depends on the method of administration of the compound, preferablyafter four days of feeding in the diet or two to twenty-four hours afteroral gavage or parenteral administration. The animal is then sacrificedand tissue samples are dissected from the animal, preferably livertissue. The type of tissue for subsequent steps of the screen isselected based upon factors including the type of free-living flatwormsused in subsequent steps of the screen, the degree to which the testcompound is circulated to a tissue type, and the target parasite. Wherethe selected tissue is liver, the dissected liver can be frozen andstored for later screening, or utilized immediately.

A portion of the dissected liver, either fresh or thawed if once frozen,is then administered to the flatworms. Administration of the liver tothe flatworms is preferably accomplished by placing a portion of theliver in a liquid medium, preferably sterilized pond water, in which theflatworms are maintained, and observing for feeding. The liver isremoved from the medium preferably within several hours fromadministration, more preferably after about two to four hours. Typicallyabout 15 to about 50 mg of liver is applied to the medium per flatworm.After administration of the liver, the activity of the flatworms isobserved and compared with that of flatworms fed on liver from untreatedanimal controls. Preferably each flatworm is kept separate from theother flatworms throughout the screen. Toxicity of the experimentalcompound is demonstrated by mortality or morbidity. Morbidity isdemonstrated by unnatural activity including rapid movement, writhing orfloating on the surface of the medium.

The ability of the screening method to detect flukicidal activity hasbeen demonstrated with known flukicides including clorsulon and thebenzimidazoles, such as albendazole, currently used for fluke control inruminants. The flukicidal activity of the Formula I' pyrrolecarbonitriles demonstrated by traditional in vivo methods has been shownby the in vitro screening method of the present invention.

Helminthiases is also caused by a group of worms referred to asnematodes. Nematodes cause serious damage to the walls and tissues ofthe organs in which they reside, including the intestinal tract, heart,lungs, and blood vessels, and are a primary cause of anemia. If leftuntreated they may result in death to the infected animals. Thenematodes most commonly found to be the infecting agents of warm-bloodedanimals include Haemonchus, Ostertagia, Cooperia, Oesphagastomum,Nematodirus, and Dictyocaulus.

The nitropyrrole and carbonitrile compounds of the following formula arepreferred for control of nematode infections and infestations: ##STR5##wherein

W is CN or NO₂ ;

X is CN, Br, Cl, I or CF₃ ;

Y is Br, Cl, I or CF₃ ;

Z is H, Br, Cl or I; and

B is hydrogen,

C₁ -C₆ alkyl optionally substituted with one to three halogen atoms,

one cyano,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms,

one phenyl optionally substituted with one to three halogen atoms, oneto three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxy groups,

one phenylcarbonyloxy group optionally substituted with one to threehalogen atoms, one to three C₁ -C₄ alkyl groups or one to three C₁ -C₄alkoxy groups, or

one C₁ -C₆ alkyloxycarbonyloxy group optionally substituted with one tothree halogen atoms,

C₃ -C₆ alkenyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ alkynyl optionally substituted with one to three halogen atoms orone phenyl group, or cyano.

Besides controlling helminths, the present invention also controlsendoparasitic arthropod infestations such as cattle grub.

It has been further found that acarid and arthropod ectoparasiticinfestations in warm-blooded animals such as lice, mange, ticks andfleas may be controlled, prevented or eliminated by the methods andcompositions of the present invention.

For control of Acarina such as ticks and mites, including the mitesresponsible for causing mange, Psoroptes cuniculi, it has been foundthat the nitropyrrole or pyrrole carbonitrile compounds of the followingstructure are preferred: ##STR6## wherein

W is CN or NO₂ ;

X is CN, Br, Cl, I or CF₃ ;

Y is H, Br, Cl, I or CF₃ ;

Z is H, Br, Cl or I; and

B is ##STR7## hydrogen, C₁ -C₆ alkyl optionally substituted with one tothree halogen atoms,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms,

one phenyl optionally substituted with one to three halogen atoms, oneto three C₁ -C₄ alkyl groups or one to three C₁ -C₄ alkoxy groups,

one C₁ -C₆ alkylcarbonyloxy group optionally substituted with one tothree halogen atoms,

one C₁ -C₆ alkoxycarbonyl group optionally substituted with one to threehalogen atoms or one to three C₁ -C₄ alkoxy groups, or

one C₁ -C₆ alkyloxycarbonyloxy group optionally substituted with one tothree halogen atoms,

C₃ -C₆ alkenyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ alkynyl optionally substituted with one to three halogen atoms orone phenyl group, or

C₁ -C₆ alkyl substituted with one to three halogen atoms and one C₁ -C₄alkoxy group;

R is phenoxy optionally substituted with one to three halogen atoms, oneor two C₁ -C₄ alkyl groups, one or two C₁ -C₄ alkoxy groups, CF₃, CN orNO₂, di(C₁ -C₄ alkyl)amino or C₁ -C₄ alkanoylamino,

C₁ -C₆ alkoxy optionally substituted with one to three halogen atoms, or

C₂ -C₆ alkenyloxy optionally substituted with one to three halogenatoms.

Among the ticks which most often infest warm-blooded animals and poultryare members of the families Ixodidae, hard ticks, and Argasidae, softticks, including ticks of the genera Boophilus, Dermacentor,Rhipicephalus, Ixodes, Amblyomna, Otobius, Argas and Ornithodoros. Thepresent invention has been found to be effective for controlling tickadults, larvae and nymphus.

The present invention has been found to be effective for controllingmites which are parasitic on warm-blooded mamals and poultry such asmites of the orders Acariformes and Parasitiformes, and particularly ofthe genera Otodectes, Psoroptes, Sarcoptes, Ornithonyssus, Demodex andChorioptes.

The present invention is also effective for controlling arthropodectoparasitic insects such as biting lice, sucking lice and fleas.Biting lice include members of Mallophaga such as Bovicola bovis,Trichodectes canis, and Damilina ovis. Sucking lice include members ofAnoplura such as Haematopinus eurysternus, Haematopinus suis,Linognathus vituli and Solenopotes capillatus.

For the control of flea infestations, including fleas of the generaCtenocephalides, Echidnophaga, Pulex and Xenopsylla, the nitropyrrole orpyrrole carbonitrile compounds of the following structure are preferred:##STR8## wherein

W is CN or NO₂ ;

X is CN, Br or Cl;

Y is H, Br or Cl;

Z is H, Br or Cl ; and

B is hydrogen,

C₁ -C₆ alkyl optionally substituted with one to three halogen atoms,

one or two C₁ -C₄ alkoxy groups optionally substituted with one to threehalogen atoms, or

one C₁ -C₆ alkyloxycarbonyloxy group optionally substituted with one tothree halogen atoms,

C₃ -C₆ alkenyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ alkynyl optionally substituted with one to three halogen atoms orone phenyl group,

C₃ -C₆ 1,2-alkadienyl, or

cyano.

For control of flea infestations, treatment of the infested animal tocontrol adults in conjunction with treatment of the area occupied by theinfested animal to control flea larvae is recommended. The compositionsof the present invention may be admixed with suitable carriers forapplication to interior and/ or exterior areas for control of flealarvae.

It has been found that helminth, acarid and arthropod endo- andectoparasitic infestations may be controlled, prevented or eliminated,by applying to, injecting or orally dosing said animals with an endo- orectoparasiticidally effective amount of the above-described formula Iand formula I' pyrrole compounds. This may be achieved by applying thecompound to the skin, hide and/or hair of the animals, or injecting ororally dosing said animals with a solid or liquid formulatedcomposition.

The compositions of the present invention may be employed as animalfeeds, animal feed premixes or feed concentrates. Feed concentrates andfeed premixes, useful in the practice of the invention, may be preparedby admixing about 0.25% to 35% by weight of the formula I or formula I'pyrrole compound with about 99.75% to 65% by weight of a suitableagronomic carrier or diluent. Carriers suitable for use include 0.75% to35% by weight of a physiologically acceptable alcohol such as benzylalcohol, phenethyl alcohol or propylene glycol, 0 to about 10% by weightof a vegetable oil such as corn oil or soybean oil, or propylene glycoland about 30% to 95% by weight of a sorptive, edible organic carriersuch as corn grits, wheat middlings, soybean meal, expanded corn grits,extracted corn meal or the like or a sorptive silica or a silicate.These feed premixes or concentrates may be admixed with the appropriateamount of animal feed to provide the animals with about 0.5 ppm to 1000ppm and preferably about 1 ppm to 500 ppm of the compound in theanimal's diet. These premixes or concentrates may also be used as topdressings for the animal's daily ration and applied across the top ofthe daily ration in sufficient amount to provide the animal with about0.5 ppm to 1000 ppm and preferably about 1 ppm to 500 ppm of the activeingredient, based on the animals total feed.

The formula I and formula I' pyrrole compounds may be administered tothe animals in or with their drinking water.

The compound may also be administered in the form of a pill, tablet,bolus, implant, capsule or drench, containing sufficient compound toprovide the treated animal with about 0.01 mg/kg to 100 mg/kg of animalbody weight per day of the compound. These dosage forms are prepared byintimately and uniformly mixing the active ingredient with suitablefinely divided diluents, fillers, disintegrating agents and/or builderssuch as starch, lactose, talc, magnesium stearate, vegetable gums or thelike. These unit dosage formulations may be varied with respect to thetotal weight and content compound depending upon the kind and size ofthe animal to be treated, the severity or type of infection encounteredand the weight of the host.

Alternately, the compound may be administered to animals parenterally,for example, by intraruminal, intramuscular or subcutaneous injection inwhich even the active ingredient is dissolved or dispersed in a liquidcarrier. For this type administration the compound may be dispersed in aphysiologically acceptable solvent for subcutaneous injection or it maybe dispersed in a fat or wax or mixture thereof containing an oil,buffer, surfactant, stabilizer, preservative and salt. Components usefulin these preparations include carbowax, aluminum monostearate gel,diethyl succinate, soya oil, glyceral dioleate, saline andcapric/caprylic triglycerides.

The formula I and formula I' pyrrole compounds may also be appliedtopically to the larger animals such as swine, sheep, cattle and horsesand companion animals such as dogs and cats in the form of aqueous dipsor sprays. For this type administration, the active compound isgenerally prepared as a wettable powder, emulsifiable concentrate,aqueous flowable or the like, which is mixed with water at the site oftreatment and applied topically to the hide, skin or hair of the animal.Such sprays or dips usually contain about 0.5 ppm to 5000 ppm andpreferably about 1 ppm to 3000 ppm of the compound.

Advantageously, the formula I and formula I' pyrrole compounds may alsobe prepared as pour-on formulations and poured on the backs of theanimals such as swine, cattle, sheep, horses, poultry and companionanimals to protect them against infestation by acarids and arthropodendo- and ectoparasites. Such pour-on compositions are generallyprepared by dis-solving, dispersing or emulsifying the formula I pyrrolecompound in a suitable nontoxic pharmacologically acceptable diluent forpour-on and administration. The diluent must be compatible with thecompound and should not be a source of irritation or damage to theanimals hide, skin or hair. Such diluents include vegetable oils,spreading oils, polyhydric alcohols, aliphatic or aromatic hydrocarbons,esters of fatty acids and lower alkyl ketones.

A typical pour-on formulation includes about 0.5% to 30% by weight ofthe formula I or formula I' pyrrole compound, about 30% to 60% by weightof an aliphatic or aromatic hydrocarbon, mono or polyhydric alcohol,lower alkyl ketone or mixtures thereof, 0 to about 20% by weight of avegetable or mineral oil and about 0.5% to 30% by weight of a spreadingoil. Another typical pour-on contains about 45% by weight of xylene,about 15% by weight of the formula I pyrrole compound, about 10% byweight of corn oil or mineral oil, about 25% by weight of cyclohexanoneand about 5% by weight of other pharmacologically acceptable spreadingagents, antifoam agents surfactants or the like.

The formula I and formula I' pyrrole compounds may also be prepared asear tags for animals, particularly quadrupeds such as cattle and sheep.The tags may be prepared by stirring together about 55% to 60% by weightof a vinyl dispersion resin, having an inherent viscosity of about 1.20and an average particle size of about 0.75 microns, a curing temperaturerange of about 120° C. to 180° C., with about 28% by weight ofbutylbenzylphthalate. Stirring is continued, and about 1.5% by weight ofca/Zn stearate stabilizer is added along with about 7.0% of the compoundand 2.8% of epoxidized soybean oil. The resulting mixture is deaeratedfor 15 to 20 minutes at 125 mm/Hg. The resulting can be coated on an eartag blank by dipping and the resulting tag cured at about 145° to 150°C. for about five minutes.

The compounds useful in this invention may be prepared by severalsynthetic routes. For example, formula I halo substituted nitropyrroles,halo substituted pyrrole carbonitriles and halo substituted nitropyrrolecarbonitriles may be prepared by halogenation of the appropriatenitropyrrole, pyrrole carbonitrile, pyrrole dicarbonitrile ornitropyrrole carbonitrile illustrated by formula II. ##STR9## wherein Wis CN or NO₂ and W' is hydrogen or CN.

Bromination of a formula II pyrrole is generally achieved by dissolutionof the formula II pyrrole in a dilute aqueous base, such as aqueoussodium hydroxide, aqueous potassium hydroxide or the like, and treatmentof the thus prepared reaction mixture with at least two to threeequivalents of bromine. The reaction may be illustrated as follows:##STR10## wherein W is CN or NO₂ ; W' is hydrogen or CN; and nrepresents the integer 3 when W' is hydrogen and the integer 2 when W'is CN. If desired, the thus prepared brominated nitropyrrole pyrrolemono- or dicarbonitrile or nitropyrrole carbonitrile, may be redissolvedin dilute aqueous base and then acidified with a mineral acid such ashydrochloric acid, to obtain the brominated pyrrole or pyrrolecarbonitrile in high purify.

It has also been found that bromination of a formula IX pyrrole may beachieved by dissolving said formula II pyrrole in an organic solventsuch as chloroform, methylene chloride, dioxane, tetrahydrofuran (THF)or the like, and admixing therewith bromine, or N-bromosuccinimidepreferably dissolved in the same organic solvent employed fordissolution of the formula II pyrrole. Gentle warming of the reactionmixture may be employed to facilitate the bromination reaction.

Since the above reactions yield a variety of brominated nitropyrroles,brominated pyrrole mono- and dicarbonitriles and brominated nitropyrrolecarbonitriles, that are formula I pyrroles by definition, but limited tobrominated products, they are identified as group IA products in thereaction illustrated above.

Chlorination of a formula II pyrrole is readily achieved by reaction ofthe formula II pyrrole with about 2 to 3 equivalents of a chlorinatingagent such as chlorine, sulfuryl chloride, or the like, in the presenceof an organic acid, such as acetic or glacial acetic acid. When sulfurylchloride is used, the reaction is generally conducted at a temperaturebelow about 40° C. and preferably between 0° C. and 30° C. The reactionmay be illustrated as follows: ##STR11## wherein W is CN or NO₂ ; W' ishydrogen or CN and n represents the integer 3 when W' is hydrogen andinteger 2 when W' is CN.

Chlorination of the formula II pyrrole may also be accomplished byreaction of said formula II pyrrole with t-butylhypochlorite or sodiumhypochlorite in the presence of am inert organic solvent at reducedtemperatures.

The group IB pyrroles, described in the above-reaction, are chlorinatednitropyrroles, chlorinated mono- and dicarbonitriles and chlorinatednitropyrrole carbonitriles, as defined by formula I but are limited tochlorinated products. As such, they are herein identified as group IBproducts.

Formation of the iodonitropyrroles, the di- and triiodopyrrolecarbonitriles or the iodonitropyrrole carbonitriles may be achieved byiodination of an appropriately substituted formula III nitropyrrolecarboxylic acid, mono- or dicyanopyrrole carboxylic acid or a cyano andnitro (substituted) pyrrole carboxylic acid dissolved in an aqueoussolution of an alkali metal carbonate or bicarbonate. In this reactionthe aqueous carbonate solution of the formula II pyrrole is treated withan aqueous solution of iodine and potassium iodide and then heated to atemperature of about 50° C. to 100° C. On cooling, the formula ICiodopyrrole is obtained. The reaction may be illustrated as follows:##STR12## wherein W is CN or NO₂ ; W' is hydrogen or CN; and n is theinteger 3 when W' is hydrogen and the integer 2 when W' is CN.

Although the formula IC products, illustrated above, are all encompassedby the definition set forth for formula I, the above reaction providesonly iodine substituted nitropyrroles, iodine substituted mono- ordicarbonitriles or iodine substituted nitropyrrole carbonitriles, thusthe products of said reaction are designated by formula IC.

Formula I products in which X, Y, and or Y and Z are represented by twodifferent halogen atoms may be prepared by first introducing one or twoequivalents of a suitable halogenating agent into a formula II pyrrolefollowed by separation of the mono- or di-halogenated pyrrole and thenadding an additional one or two equivalents of a second halogenatingagent to give the formula I tetrasubstituted pyrrole.

Preparation of B-substituted formula I halonitropyrroles, halopyrrolecarbonitriles and halonitropyrrole carbonitriles may be achieved byreaction of the appropriately substituted formula I pyrrole having B ashydrogen with an alkylating or acylating agent in the presence of analkali metal alkoxide or hydride. More particularly, preparation of theB substituted formula I pyrrole involves reaction of formula I pyrrole:##STR13## wherein B is hydrogen and W, X, Y and Z are as described informula I above, with an appropriate alkylating agent such as a C₁ -C₆alkylhalide in which the alkyl group is straight or branched and isoptionally substituted with from one to three halogen atoms, onehydroxy, one cyano, one C₁ -C₄ alkoxy, one C₁ -C₄ alkylthio, one phenylgroup, optionally substituted with from one to three halogen atoms, orone benzyloxy group, optionally substituted with from one to threehalogen atoms, and an alkali metal alkoxide such as sodium or potassiumt-butoxide. This reaction provides a halo nitropyrrole, halopyrrole(mono- or di) carbonitrile or halonitropyrrole carbonitrile having thesame substituents as the starting material, but in addition issubstituted on the nitrogen with a C₁ -C₆ alkyl group optionallysubstituted as described above. The reaction may be illustrated asfollows: ##STR14## In a similar reaction cyanogen bromide is substitutedfor the alkylhalide and yields the formula I halo substitutednitropyrrole, halopyrrole carbonitrile or halonitropyrrole carbonitrilehaving a carbonitrile, rather than an alkyl group, on the nitrogen.Formula IA, IB and IC compounds may also be alkylated in accordance withthe above procedure by substituting a compound according to formula IA,IB or IC for the formula I pyrrole in which W, X, Y and Z representsubstituents as described above and B is hydrogen.

Advantageously, the above-described alkylation procedure of the formulaI, IA, IB and IC, halo (substituted) pyrroles, in which B is hydrogen,may also be applied to the preparation of formula I halopyrroles havingan N--C₃ -C₆ alkenyl or N--C₃ -C₆ alkynyl substituent. ThisN-substitution may be obtained by simply substituting a C₃ -C₆ alkenylhalide or C₃ -C₆ alkynyl halide for the C₁ -C₆ alkyl halide in theabove-described reaction.

In a similar manner, preparation of N-acylated halonitropyrroles,halopyrrole carbonitriles and halonitropyrrole carbonitriles may beachieved by the reaction of an appropriately substituted formula Ipyrrole wherein B is hydrogen with an acylating agent in the presence ofan alkalai metal alkoxide. Acylating agents such as C₁ -C₆ alkyl or C₂-C₆ alkenyl acid chloride, substituted C₁ -C₆ alkyl or C₂ -C₆ alkenylacid chloride, benroyl chloride, substituted benzoyl chloride,phenylchloroformate, substituted phenylchloroformate, C₁ -C₆ alkyl or C₂-C₆ alkenylchloroformate, substituted C₁ -C₆ alkyl or C₂ -C₆alkenylchloroformate, N-substituted carbamoyl chloride and the like maybe employed. The reaction may be illustrated as follows: ##STR15##wherein A is halogen, M is alkalai metal and W, X, Y, Z and R are asdescribed hereinabove for formula I.

Preparation of (trifluoromethyl)pyrrole carbonitriles and conversionthereof to dihalo (trifluoromethyl)pyrrole carbonitriles and dihalo-alkylated N-(trifluoromethyl)pyrrole carbonitriles can be achieved bythe admixture of a dispersion of sodium hydride in tetrahydrofuran witha solution of ethyl trifluoroacetate and 3-cyano propionaldehyde diethylacetal in tetrahydrofuran. The reaction that occurs yields3-trifluoroacetyl-3-cyanopropionaldehyde diethyl acetal which is thenheated with oxalic acid dihydrate in water to give the3-trifluoroacetyl-3-cyanopropionaldehyde. The thus prepared aldehyde isthen dissolved in glacial acetic acid and the resulting solution treatedwith ammonium acetate to provide the2-(trifluoromethyl)pyrrole-3-carbonitrile. Halogenation of theabove-said (trifluoromethyl)pyrrole carbonitrile may then beaccomplished by reaction of said (trifluoromethyl)pyrrole carbonitrilewith N-bromosuccinimide or N-chlorosuccinimide in the presence oftetrahydrofuran to yield the dihalo (trifluoromethyl)pyrrolecarbonitrile. Alkylation or acylation of this dihalo(trifluoromethyl)pyrrole carbonitrile with an alkyl halide or acylhalidein the presence of potassium t-butoxide and tetrahydrofuran yields theN-alkylated (or N-acylated) dihalo (trifluoromethyl)pyrrolecarbonitrile.

Other methods for the preparation of the formula I halo substitutednitropyrroles, halo substituted pyrrole carbonitriles, halo substitutednitropyrrole carbonitriles and the N-substituted derivatives thereof,will become apparent from the examples set forth below.

The formula I' pyrrole carbonitriles are prepared similarly to theformula I compounds as set forth herein.

EXAMPLE 1 Evaluation of Test Compounds as Nematocidal Agents

Cultures of C. elegans (Bristol strain from J. Lewis) are maintained onE. coli lawns on NG Agar Plates at 20° C. New cultures are establishedweekly.

Nematodes for testing are washed from 4-5 day old cultures using RingersSolution.

Compounds are dissolved in acetone and made up to volume with equalparts of water. The final test concentration of each compound is 150ppm. The test material is micropipetted (25 ul) into a single well of a96-well sterile tissue culture plate and the solvent allowed toevaporate. These "treated" plates are used immediately or stored in afreezer without apparent adverse effects on the compounds.

A freshly prepared volume (50 μl) of C. elegans in Ringers Solution ismicropipetted into each treated well and several control wells perplate. Culture plate are incubated at 20° C.

Observations for efficacy are made under a dissecting microscope at 4and 24 hours post-immersion. Immediately prior to reading the plate, itis gently tapped to stimulate the movement of the worms. Activity isjudged subjectively, but semi-quantitatively, based on the drug effectson motility on the adults and larvae. The criteria are as follows:9=complete kill, 8=no motility, 7=markedly reduced motility inapproximately 95% of worms and 0=normal motility, same as controls.Other factors indicating activity are easily noted such as death, rigormortis, contraction, coiling, paralysis, abnormal twitching, reducedworm population and other deviation from normal behavior.

    ______________________________________                                        PROCEDURE FOR CAENORHABDITIS ELEGANS ASSAY                                    ______________________________________                                        Day 0      Inoculate E. Coli-NG Agar Dish With 30-40                                     C. Elegans                                                                    Incubate At 20° C.                                          Day 4      Harvest New C. Elegans Population                                             Add C. Elegans (50 UL) To "Medicated"                                         Wells.sup.a                                                                   Observe for Activity at 4 hours Post-                                         Immersion                                                          Day 5      Observe For Activity                                               ______________________________________                                         .sup.a Medicated Wells May Be Prepared Fresh or Earlier and Stored In         Freezer                                                                  

Data obtained in these tests are reported in Table I below.

                  TABLE I                                                         ______________________________________                                        Evaluation of Formula I Pyrrole Activity                                      Against C. Elegans                                                                                Rating Against                                            Formula I Compound  C. Elegans 150 ppm                                        ______________________________________                                        2-Chloro-4-nitropyrrole                                                                           9                                                         2,5-Dichloro-3-nitropyrrole                                                                       9                                                         2,3-Dichloro-4-nitropyrrole                                                                       9                                                         2,3,5-Trichloro-4-nitropyrrole                                                                    9                                                         2,5-Dibromo-3-nitropyrrole                                                                        9                                                         2,3-Dibromo-4-nitropyrrole                                                                        9                                                         2,4,5-Trichloropyrrole-3-                                                                         9                                                         carbonitrile                                                                  4,5-Dichloropyrrole-3-                                                                            9                                                         carbonitrile                                                                  2,4,5-Tribromopyrrole-3-                                                                          9                                                         carbonitrile                                                                  2,4,5-Trichloro-1-methylpyrrole-                                                                  9                                                         3-carbonitrile                                                                2,4,5-Tribromo-1-methylpyrrole-                                                                   9                                                         3-carbonitrile                                                                2,4,5-Tribromopyrrole-1,3-di-                                                                     9                                                         carbonitrile                                                                  4,5-Dibromopyrrole-2-carbonitrile                                                                 9                                                         3,4,5-Tribromopyrrole-2-carbonitrile                                                              9                                                         3,4,5-Tribromopyrrole-2-carbonitrile                                                              9                                                         3,4,5-Tribromo-1-methylpyrrole-2-                                                                 9                                                         carbonitrile                                                                  2,5-Diiodo-1-methylpyrrole-3-                                                                     9                                                         carbonitrile                                                                  5-Nitropyrrole-5-carbonitrile                                                                     9                                                         4-Nitropyrrole-2-carbonitrile                                                                     9                                                         3,4-Dibromo-5-nitropyrrole-2-                                                                     9                                                         carbonitrile                                                                  3,5-Dibromo-4-nitropyrrole-2-                                                                     9                                                         carbonitrile                                                                  1-(Ethoxymethyl)-5-nitropyrrole-                                                                  9                                                         2-carbonitrile                                                                1-Allyl-2,4,5-Tribomopyrrole-3-                                                                   9                                                         carbonitrile                                                                  4,5-Dibromo-1-(ethoxymethyl)-2-                                                                   9                                                         (trifluoromethyl)pyrrole-3-                                                   carbonitrile                                                                  ______________________________________                                    

EXAMPLE 2 Evaluation of Nitropyrroles and Pyrrole Carbonitriles AgainstCtenocephalides felis, the Cat Flea

On the day prior to the test initiation the drugs to be evaluated aredissolved in acetone and diluted to the desired concentrations. Theconcentration is calculated so that 400 μl contains the amount of testcompound to be placed on each filter paper. 400 μl of this solution ispipetted onto a (3.7 cm diameter) filter paper disk which is then placedon a ceramic plate to dry. There is a rough and smooth side to thefilter paper. Drug should be applied to the rough side to the filterpaper and placed up while drying. When dry, the disk is placed in aPetri dish with the rough side facing up and then held at roomtemperature overnight if done the day before the test.

(1) Unfed fleas that have emerged from pupae within the last 24 hoursare used for the test. Fleas are initially collected in glass vials andthen temporarily immobilized by placing the vials in ice. Once the fleasare no longer active, vials are opened and fleas dumped into Petridishes. The number of fleas per dish will vary but generally will be8-12 fleas.

(2) Edges of the Petri dish are sealed with Scotch tape to preventescape of the fleas.

(3) Dishes are held for 24 hours before the mortality counts are made.

(4) Dishes are not opened when the test is read but fleas in the dishesare observed under dissecting scope. Some fleas will move under thefilter paper so the dish should be inverted to check. Fleas areconsidered dead if they cannot remain upright and jump.

(5) Percent mortality of the fleas, corrected for control mortality, isthen calculated for each treatment.

Data obtained are reported in Table II below.

                  TABLE II                                                        ______________________________________                                        Evaluation of nitropyrroles and pyrrole carbonitriles                         against Ctenocephalides felis, the cat flea                                                              24 hour                                            Compound           μg/cm.sup.2                                                                        % Mortality                                        ______________________________________                                        2,4,5-Tribromo-1-methyl-                                                                         10      100                                                pyrrole-3-carbonitrile                                                                           1       100                                                4,5-Dibromo-1-methylpyrrole-                                                                     10      100                                                2-carbonitrile     1       10                                                 3,4,5-Tribromo-1-methyl-                                                                         10      100                                                pyrrole-2-carbonitrile                                                                           1       100                                                3,4,5-Tribromo-1-(2-pro-                                                                         10      100                                                pynyl)-pyrrole-2-carbo-                                                                          1       100                                                nitrile                                                                       3,4,5-Tribromopyrrole-2-                                                                         10      100                                                carbonitrile                                                                  4,5-Dibromopyrrole-2-                                                                            10      100                                                carbonitrile       1       100                                                2,3,5-Trichloro-1-methyl-                                                                        10      97                                                 pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-(2-pro-                                                                         10      92                                                 pynyl)-pyrrole-3-carbo-                                                       nitrile                                                                       3,5-Dibromo-1-methyl-                                                                            10      18                                                 pyrrole-2,3-dicarbonitrile                                                    2,4,5-Tribromopyrrole-1,3-                                                                       10      98.5 avg.                                          dicarbonitrile             2 reps.                                            3,4,5-Tribromo-1-(1,2-                                                                           10      100                                                propadienyl)pyrrole-2-                                                                           1       100                                                carbonitrile                                                                  2-Bromo-1-methyl-4-                                                                              10      100                                                nitropyrrole                                                                  2,4,5-Tribromo-1-  10      100                                                (methoxymethyl)pyrrole-                                                                          1       100                                                3-carbonitrile                                                                ______________________________________                                    

EXAMPLE 3 Evaluation of Nitropyrroles and Pyrrole Carbonitriles AgainstPsoroptes cuniculi

On the day prior to the test initiation the drugs to be evaluated aredissolved in acetone and diluted to the desired concentrations. Theconcentration is calculated so that 400 μl contains the amount of testcompound to be placed on each filter paper. 400 μl of this solution ispipetted onto top (3.7 cm dia.) and bottom (3.5 cm dia.) filter paperdisks which are then placed on a ceramic plate to dry. There is a roughand smooth side to the filter paper. Drug should be applied to the roughside which is placed up while drying. When dry the two disks are placedin a Petri dish with the rough sides facing in, separated by one 3 mmglass bead. Dishes are held at room temperature overnight if preparedthe day before the test.

Scab (containing mites) is collected from the ears of infested rabbitsthe morning of the test. This material is placed in a large Petri dishunder an illuminated magnifier. Mites crawl out of the scab and areeasily collected on the point of a dissecting needle or one prong of apair of fine forceps. The top filter paper in each dish is removed and12 mites are placed on the bottom disk and the top paper replaced.Before replacing the top of the Petri dish the rim of the dish issmeared with petroleum jelly to trap any escaping mites. After mites areadded to the dishes, the dishes in each replicate are placed in a traywhich is then placed in a plastic bag with several wet towels and heldat room temperature.

For evaluation tests there are generally 4 replicates of each dose whichare counted at 24 hours. After 24 hours the dishes are examined under adissecting scope. Each dish is opened carefully and the top filter paperremoved and saved. A 1/2 cm circle is drawn on the bottom filter paperand the paper gently wet in the area of the circle. All mites from thedish and top filter paper are transferred into the wet circle area andcounted. The top cover is replaced on each dish and the dishes set asidefor at least 15 minutes. After standing the dishes are examined and themites remaining in the circle counted. These mites are dead. Percentmortality of the mites, corrected for control mortality, is thencalculated for each treatment. These data are reported in Table IIIbelow.

                  TABLE III                                                       ______________________________________                                        Evaluation of nitropyrroles and pyrrole                                       carbonitriles against Psoroptes cuniculi                                      (Rabbit Ear Mite)                                                                                        24 hour                                            Compound           μg/cm.sup.2                                                                        % Mortality                                        ______________________________________                                        4,5-Dibromopyrrole-2-                                                                            4       100                                                carbonitrile       1       100                                                3,4,5-Tribromo-1-methyl-                                                                         4       100                                                pyrrole-2-carbonitrile                                                                           1       58                                                 2,5-Diiodo-1-methyl-                                                                             4       100                                                pyrrole-3-carbonitrile                                                                           1       100                                                2,4,5-Tribromo-1-methyl-                                                                         4       14                                                 pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-(ethoxy-                                                                        4       54                                                 methyl)pyrrole-3-carbonitrile                                                 3,4,5-Tribromopyrrole-                                                                           4       100                                                2-carbonitrile     1       89                                                 Pyrrole-3,4-dicarbonitrile                                                                       4       12                                                 4-Nitropyrrole-2-carbonitrile                                                                    4       44                                                 1-Methyl-5-nitropyrrole-2-                                                                       4       92                                                 carbonitrile                                                                  1-Allyl-2,4,5-tribromopyrrole-                                                                   4       37                                                 3-carbonitrile                                                                3,4,5-Tribromo-1-(2-propynyl)-                                                                   4       100                                                pyrrole-2-carbonitrile                                                                           1       100                                                4,5-Dibromo-2-(trifluoro-                                                                        4       11                                                 methyl)pyrrole-3-carbonitrile                                                 4,5-Dibromo-1-methylpyrrole-                                                                     4       100                                                3-carbonitrile                                                                4,5-Dibromo-1-(ethoxymethyl)-                                                                    4       100                                                2-(trifluoromethyl)pyrrole-                                                   3-carbonitrile                                                                2,4,5-Tribromo-1-(hydroxy-                                                                       4       100                                                methyl)pyrrole-3-carbonitrile,                                                                   1       86                                                 pivalate (ester)                                                              2,4,5-Tribromo-1-(3,4-dichloro-                                                                  4       100                                                benzyl)pyrrole-3-carbonitrile                                                                    1       19                                                 tert-Butyl 2,3,5-tribromo-4-                                                                     4       5                                                  cyanopyrrole-1-acetate                                                        2,4,5-Tribromo-1-(isopropoxy-                                                                    4       100                                                methyl)pyrrole-3-carbonitrile                                                 2,4,5-Tribromo-1-(2-chloro-1-                                                                    4       100                                                ethoxyethyl)pyrrole-3-carbo-                                                                     1       100                                                nitrile                                                                       2,4,5-Tribromo-1-(hydroxy-                                                                       4       91                                                 methyl)pyrrole-3-carbonitrile,                                                acetate (ester)                                                               Ethyl 1-(2,3,5-tribromo-4-                                                                       4       100                                                cyanopyrrol-1-yl)ethylcarbonate                                                                  1       46                                                 Phenyl 2,3,5-tribromo-4-                                                                         4       41                                                 cyanopyrrole-1-carboxylate                                                    2,4,5-Tribromo-1-(methoxy-                                                                       4       100                                                methyl)pyrrole-3-carbonitrile                                                                    1       95                                                 ______________________________________                                    

EXAMPLE 4 Evaluation of Test Compounds Against the Newly Hatched Larvaeof the Dogtick, Dermacentor variabilis

The test procedure used herein is the same procedure described in NewExample 3, for evaluating ing test compounds for control of Psoroptescuniculi the Rabbit Ear Mits, with the following exceptions:

(1) Unfed larval ticks are obtained from egg masses laid by gravidfemale ticks removed from dogs and each replicate receives ticks fromthe same egg mass; and

(2) When reading the test it may be necessary to blow on the ticks tostimulate their movement.

Data obtained are reported in Table IV below.

                  TABLE IV                                                        ______________________________________                                        Evaluation of Formula I pyrroles against the larval                           stage of the Dogtick, Dermacentor variabilis                                                             24 hour                                            Formula I Compound μg/cm.sup.2                                                                        % Mortality                                        ______________________________________                                        2,4,5-Tribromopyrrole-3-                                                                         10      95                                                 carbonitrile                                                                  2,4,5-Tribromo-1-methyl-                                                                         10      100                                                pyrrole-3-carbonitrile                                                                           1       82                                                 2,4,5-Tribromo-1-(ethoxy-                                                                        1       5                                                  methyl)pyrrole-3-carbo-                                                       nitrile                                                                       4,5-Dibromopyrrole-2-                                                                            10      100                                                carbonitrile       5       100                                                                   1       100                                                3,4,5-Tribromo-1-methyl-                                                                         10      90                                                 pyrrole-2-carbonitrile                                                        2,5-Diiodo-1-methyl-                                                                             10      100                                                pyrrole-3-carbonitrile                                                                           5       100                                                                   1       75                                                 3,4,5-Tribromo-1-(2-                                                                             10      100                                                propynyl)pyrrole-2-                                                                              5       100                                                carbonitrile       1       69                                                 2,4,5-Tribromo-1-(hydroxy-                                                                       10      100                                                methyl)pyrrole-3-carbo-                                                       nitrile, pivalate (ester)                                                     2,4,5-Tribromo-1-(isopro-                                                                        10      95                                                 poxymethyl)pyrrole-3-                                                         carbonitrile                                                                  Allyl 2,3,5-tribromo-4-                                                                          10      100                                                cyanopyrrole-1-carboxylate                                                                       5       94                                                 2,4,5-Tribromo-1-(methoxy-                                                                       10      100                                                methyl)pyrrole-3-carbo-                                                                          5       100                                                nitrile            1       74                                                 ______________________________________                                    

EXAMPLE 5 Evaluation of Test Compounds Against Dugesia tigrina andPhagocata morgani (Planaria)

The flukicidal activity of test compounds is demonstrated in thefollowing tests. Test compounds are administered to gerbils in the diet,by a single oral gavage dose or by a single subcutaneous injection atthe dosage indicated. After 4 days of feeding or 2-24 hourspost-treatment in the case of oral gavage or subcutaneousadministration, the gerbils are sacrificed and their livers are removed.Frozen liver which has been thawed, or fresh liver, is then fed toindividual planaria in small dishes containing sterilized pond water.The planaria are observed to see if feeding occurs. Livers are removedafter 2-4 hours. Planaria are then observed for 3-4 days and theiractivity is compared to controls fed liver from untreated gerbils.Toxicity is demonstrated by death and unnatural activity such as rapidmovement, writhing or floating on the surface. Data obtained arereported in Table V below. The rating system employed is as follows:

    ______________________________________                                        Rating System                                                                 ______________________________________                                        +        =             Toxic effect observed                                  ±     =             Possible toxic effect                                                         observed                                               0        =             No toxic effect                                                               observed                                               -        =             Not tested                                             ______________________________________                                    

                                      TABLE V                                     __________________________________________________________________________    Evaluation of compounds against Dugesia tigrina                               and Phagocata morgani (Planaria)                                                                         Efficacy                                           Compound      PPM in Diet  Dugesia tigrina                                                                      Phagocata morgani                           __________________________________________________________________________    2,4,5-Tribromopyrrole-3-                                                                     20          -      0                                           carbonitrile   50          -      0                                                         100          -      ±                                                      Single oral dose                                                              10 mg/kg, sacrificed 5.5 hr                                                                0      ±                                                      post-administration                                             2,4,5-Tribromo-1-methyl-                                                                     10          0      0                                           pyrrole-3-carbonitrile                                                                       50          0      0                                                         100          ±   0                                           2,4,5-Tribromo-1-(ethoxy-                                                                   100          ±   -                                           methyl)pyrrole-3-carbo-                                                       nitrile                                                                       2,4,5-Tribromo-1-ethyl-                                                                     100          0      0                                           pyrrole-3-carbonitrile                                                                      Single oral dose                                                              10 mg/kg, sacrificed 5.5 hr                                                                -      +                                                         post-administration                                             1-Allyl-2,4,5-tribromo-                                                                     100          0      0                                           pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-(hydroxy-                                                                   20          -      0                                           methyl)pyrrole-3-carbo-                                                                      50          -      ±                                        nitrile, pivalate (ester)                                                                   100          +      ±                                                      Single subcutaneous injection                                                 10 mg/kg, sacrificed 2 hr                                                                  +      -                                                         post-administration                                             2,4,5-Tribromo-1-(isopro-                                                                   100          ±   +                                           poxymethyl)pyrrole-3-                                                                       Single oral dose                                                carbonitrile  10 mg/kg, sacrificed 8 hr                                                                  -      0                                                         post-administration                                             2,4,5-Tribromo-1-(p-                                                                        500          -      0                                           chlorophenacyl)pyrrole-                                                       3-carbonitrile                                                                2,4,5-Tribromo-1- (tri-                                                                     500          0      -                                           methylsilyl)methyl!-                                                          pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-(2-                                                                        100          ±   -                                           chloro-1-ethoxyethyl)-                                                                      500          ±   -                                           pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-(hydroxy-                                                                  100          ±   -                                           methyl)pyrrole-3-carbo-                                                                     500          ±   -                                           nitrile, acetate (ester)                                                      Ethyl 1-(2,3,5-tribromo-                                                                    100          -      0                                           4-cyanopyrrol-1-yl)ethyl-                                                                   500          ±   -                                           carbonate                                                                     2,4,5-Tribromo-1-(p-                                                                        100          0      +                                           chlorobenzoyl)pyrrole-3-                                                                    250          0      +                                           carbonitrile  Single oral dose                                                              10 mg/kg, sacrificed 6 hr                                                                  0      +                                                         post-administration                                             Phenyl 2,3,5-tribromo-4-                                                                    100          0      -                                           cyanopyrrole-1-carboxylate                                                    2,4,5-Tribromo-1-(p-chloro-                                                                 100          -      ±                                        benzyl)pyrrole-3-carbo-                                                       nitrile                                                                       2,4,5-Tribromo-1-(hydroxy-                                                                  100          -      0                                           methyl)pyrrole-3-carboni-                                                     trile, benzoate (ester)                                                       Methyl 2,3,5-tribromo-4-                                                                    100          -      +                                           cyanopyrrole-1-carboxylate                                                    Vinyl 2,3,5-tribromo-4-                                                                     100          ±   -                                           cyanopyrrole-1-carboxylate                                                    3,4,5-Tribromo-1-(2-chloro-                                                                 100          0      -                                           1-ethoxyethyl)pyrrole-2-                                                      carbonitrile                                                                  3,4,5-Tribromo-1-(ethoxy-                                                                   100          -      0                                           methyl)pyrrole-2-carbo-                                                       nitrile                                                                       2,4,5-Tribromo-1-(p-                                                                        500          ±   +                                           methoxybenzoyl)pyrrole-                                                       3-carbonitrile                                                                Allyl 2,3,5-tribromo-4-                                                                     100          +      ±                                        cyanopyrrole-1-carbo-                                                                       Single oral dose                                                xylate        10 mg/kg, sacrificed 8 hr                                                                  +      -                                                         post-administration                                                           10 mg/kg, sacrificed 25 hr                                                                 -      +                                                         post-administration                                                           Single subcutaneous injection                                                 10 mg/kg, sacrificed 24 hr                                                                 -      ±                                                      post-administration                                             (2,3,4-Tribromo-5-cyano-                                                                    500          0      0                                           pyrrol-1-yl)methyl pivalate                                                   2,5-Dibromo-1-(ethoxy-                                                                       25          -      0                                           methyl)-4-(trifluoromethyl)-                                                  pyrrole-3-carbonitrile                                                        2,5-Dibromo-1-(2-chloro-1-                                                                  100          +      -                                           ethoxyethyl)-4-(trifluoro-                                                    methyl)pyrrole-3-carbo-                                                       nitrile                                                                       2,4,5-Tribromo-1-pivaloyl-                                                                  500          0      -                                           pyrrole-3-carbonitrile                                                        2,5-Dibromopyrrole-3,4-                                                                     500          -      0                                           dicarbonitrile                                                                2,4,5-Tribromo-1-(methoxy-                                                                   50          -      +                                           methyl)pyrrole-3-carbo-                                                                     100          -      +                                           nitrile       500          0      +                                           2,5-Dibromo-1-methyl-                                                                       500          0      ±                                        pyrrole-3,4-dicarbonitrile                                                    2,4,5-Tribromo-1-(bromo-                                                                    100          -      0                                           methyl)pyrrole-3-carbo-                                                       nitrile                                                                       2,5-Dibromo-1-(ethoxy-                                                                      500          0      0                                           methyl)pyrrole-3,4-dicar-                                                     bonitrile                                                                     2,4,5-Tribromo-1-(chloro-                                                                   250          -      ±                                        methyl)pyrrole-3-carbo-                                                                     500          ±   +                                           nitrile       Single oral dose                                                              50 mg/kg, sacrificed 6 hr                                                                  0      ±                                                      post-administration                                                           50 mg/kg, sacrificed 2 hr                                                                  -      0                                                         post-administration                                             4,5-Dibromo-1-(tert-                                                                        500          -      0                                           butoxymethyl)pyrrole-3-                                                       carbonitrile                                                                  Albendazole   Single oral dose                                                              100 mg/kg, sacrificed 8 hr                                                                 +      ±                                                      post-administration                                             Clorsulon     100          -      +                                                          25          -      +                                           __________________________________________________________________________

EXAMPLE 6 Evaluation of Test Compounds Against Faciola hepatica (LiverFluke)

Female Wistar rats are infected with 20 Faciola hepatica metacercariaeand allocated to 22 test groups of 10 rats each. Each group of rats istreated by oral gavage or by subcutaneous injection with a single doseof test compound at the dosage indicated, at 2, 10 or 12 weekspost-infection. Four groups of 12 untreated rats infected with 20Faciola hepatica metacercariae serve as the control. Feed and water areoffered ad libitum. Each group of rats is sacrificed at 12 or 14 weekspost-infection and examined for flukes. The number of flukes recoveredfrom treated rats is compared with the number recovered from infecteduntreated controls. The data obtained are reported in Table VI below.

                  TABLE VI                                                        ______________________________________                                        Evaluation of Formula I' Compounds Against                                    Fasciola hepatica (Liver Fluke)                                                                  % Fluke Reduction                                                    Oral     Treatment Week/                                                      Dose     Sacrifice Week                                             Formula I' Compound                                                                       mg/kg      2/12   2/14  10/12 12/14                               ______________________________________                                        2,4,5-Tribromo-1-                                                                         25         100    88    92    100                                 (hydroxymethyl)-                                                                          8.3        90     --    100   --                                  pyrrole-3-carbo-                                                                          Subcutaneous                                                      nitrile     Injection                                                         pivalate (ester)                                                                          10         95     --    --    --                                              5          --     --    71    --                                  2,4,5-Tribromo-1-                                                                         20         93     --    --    --                                  methyl-pyrrole-3-                                                                         12         --     --    100   --                                  carbonitrile                                                                              6.7        92     --    --    --                                              4          --     --    85    --                                  2,4,5-Tribromo-1-                                                                         10         92     --    90    --                                  (methoxymethyl)-                                                                          3.3        53     --    85    --                                  pyrrole-3-carbo-                                                              nitrile                                                                       2,4,5-Tribromo-1-                                                                         10         --     80    --    100                                 (isopropoxymethyl)-                                                           pyrrole-3-carbo-                                                              nitrile                                                                       2,4,5-Tribromo-1-                                                                         10         --     80    --    100                                 (p-chlorobenzoyl)-                                                            pyrrole-3-                                                                    carbonitrile                                                                  Allyl 2,3,5-tri-                                                                          10         --     90    --    100                                 bromo-4-cyano-                                                                pyrrole-1-carboxylate                                                         ______________________________________                                    

EXAMPLE 7 Evaluation of Test Compounds for Control of Nematodes inWarm-Blooded Aimals

Each test generally consists of 75 infected gerbils, randomlydistributed 2 or 3 per cage (the number of animals per cage isconsistent within a specific experiment). Generally, there are 8-9untreated control gerbils (3-4 cages) per test. The remaining cages areassigned a treatment, usually 1 cage per compound or dose.

Compounds administered in diet are fed for 4 days. Animals treated bygavage or injection are generally treated on day 7.

In accordance with this test, gerbils are each orally infected bygavage, with about 400 Trichostrongylus colubriformis infective larvaeof sheep origin. The infected animals are then permitted to feed anddrink ad libitum for six days. On day 7 the infected gerbils arerandomly placed in rodent cages, 2 or 3 animals per cage. The animals ineach cage are weighed and the feed for each cage weighed. If thetreatment to be evaluated is medicated feed, said medicated feed isoffered on day 7 and continued through day 11 of the trial. If thetreatment to be evaluated is a single oral dose or a parenteratreatment, the animals are given the medication by gavage or injectionon day 7 and receive unmedicated feed and water through day 11 of thetrial. On day 11 the animals and their feed are weighed. Thereafter theanimals are euthanized by CO₂ inhalation and their small intestinesremoved, inverted on application sticks and incubated in tap water at39° C. for 1.5 hours. The sticks and intestines are then discarded andthe worms from each treatment counted to determine the % mortality ofthe worms as compared to untreated controls. Data obtained are reportedin Table VII below.

                  TABLE VII                                                       ______________________________________                                        Evaluation of Formula I compounds                                             against T. colubriformis in Gerbils                                                              PPM in  % Nematode                                         Formula I Compound Diet    removal                                            ______________________________________                                        2,4,5-Trichloro-1-methyl-                                                                        50      51                                                 pyrrole-3-carbonitrile                                                        2,4,5-Tribromo-1-methyl-                                                                         100     18                                                 pyrrole-3-carbonitrile                                                        2,4,5-Tribromopyrrole-1,3-                                                                       100     54                                                 dicarbonitrile                                                                4,5-Dibromo-1-methylpyrrole-                                                                     500     25                                                 2-carbonitrile                                                                3,4,5-Tribromopyrrole-2-                                                                         125     31                                                 carbonitrile                                                                  4,5-Dibromopyrrole-2-                                                                            500     6                                                  carbonitrile                                                                  3,4,5-Tribromo-1-(2-                                                                             500     9                                                  propynyl)pyrrole-2-                                                           carbonitrile                                                                  ______________________________________                                    

EXAMPLE 8 Preparation of 1-Methyl-5-Ntropyrrole-2-Crbonitrile

To a solution of 300 mg of 5-nitropyrrole-2-carbonitrile (2.14 mmol) in15 mL of acetone, 360 mg of potassium carbonate (2.6 mmol) and 0.165 mLof iodomethane (1.6 mmol, 372 mg) are added. The mixture is then stirredat room temperature for 24 hours. The reaction mixture is poured intoice-water (100 mL) and the precipitate which forms is collected to yield(200 mg), 62%; mp 86°-87° C. of 1-methyl-5-nitropyrrole-2-carbonitrile.

EXAMPLE 9 Preparation of 1-Ethoxymethyl-5-Nitropyrrole-2-Carbonitrile

To a solution of 560 mg of 5-nitropyrrole-2-carbonitrile (4 mmol) in 20mL of dry THF, is added 515 mg of potassium tert-butoxide (4.6 mmol).After the addition of 0.45 mL of chloromethylethylether (4.8 mmol) tothe mixture, the mixture is stirred for 4 hours, then diluted with ether(30 mL) and water (50 mL). The organic layer is separated, washed withwater MgSO₄ (20 mL) and dried over MgSO₄. After evaporation of thesolvent a red oil is obtained (600 mg, 75%)1-(ethoxlmethyl)-5-nitropyrrole-2-carbonitrile.

Anal. Calcd: C, 49.23%; H, 4.65%; N, 21.53%.

Found: C, 49.40%; H, 4.07%; N, 21.30%.

EXAMPLE 10 Preparation of 3-Trifluoroacetyl-3-CyanopropionaldehydeDiethyl Acetal ##STR16##

To a 40°-45° C. stirring suspension of hexane-washed sodium hydride (5.5g of a 60% dispersion, 0.14 mol) in 200 mL of dried tetrahydrofuran isadded dropwise a solution of ethyl trifluoroacetate (15 g, 0.11 mol) and3-cyanopropionaldehyde diethyl acetal (17 g, 0.11 mol) in 100 mL of drytetrahydrofuran. The previously gray suspension slowly turns light brownin color. The reaction mixture is stirred at 50°-55° C. overnight beforebeing quenched by slow addition of 2-propanol (15 mL). Rotaryevaporation of the volatiles yields a dark oil, to which is added 150 mLof pH 7 water. Unreacted starting materials are conveniently removed bywashing the aqueous layer with diethyl ether (3×30 mL). The basicaqueous phase is then acidified with 12N hydrochloric acid and extractedwith ethyl acetate (2×100 mL). The combined organic layers are washedonce with saturated sodium bicarbonate (40 mL) and once with brine (15mL) before being dried over magnesium sulfate. Rotary evaporation yieldsa reddish oil which is flash chromatographed over silica gel using 4:1hexane-ethyl acetate as eluent to provide the desired product (9 g, 32%)as a yellow oil.

EXAMPLE 11 Preparation of 3-Trifluoroacetyl-3-Cyanopropionaldehyde##STR17##

A mixture of the 2-trifluoroacetylcyanopropionaldehyde-4,4-diethylacetal (5.0 g, 0.02 mol) and oxalic acid dihydrate (1.2 g, 0.01 mol) in75 mL of water is heated to reflux for 20 minutes. After the reaction isallowed to cool, sodium bicarbonate (1.7 g, 0.02 mol) is added followedby 100 mL of ethyl acetate. The layers are separated and the organicphase is washed once with brine (15 mL) before being dried overmagnesium sulfate. Rotary evaporation yields a dark oil which is usedimmediately in the next step of the reaction sequence.

EXAMPLE 12 Preparation of 2-(Trifluoromethyl)Pyrrole-3-Carbonitrile##STR18##

The crude aldehyde (isolated from the previous step (4.5 g) is dissolvedin 50 mL of glacial acetic acid, followed by ammonium acetate (1.5 g,0.02 mol). The mixture is heated to 65°-70° C. for one hour, allowed tocool, and is then poured into 100 mL of water. Extraction with ethylacetate (2×75 mL) is followed by bicarbonate washing of the combinedorganic phases until no acid remains. The red solution is then driedover magnesium sulfate and rotary evaporated to a dark oil. Purificationover silica gel using 4:1 hexane-ethyl acetate as eluent affords the2-trifluoromethyl-3-cyanopyrrole (0.7 g, 4.3 mmol, 22% from the acetal)as a light yellow solid, mp 122°-124° C.

EXAMPLE 13 Preparation of4,5-Dibromo-2-(Trifluoromethyl)Pyrrole-3-Carbonitrile ##STR19##

To a solution of 2-(trifluoromethyl)pyrrole-3-carbonitrile (1.0 g, 6.2mmol) in 40 mL of tetrahydrofuran is added N-bromosuccinimide (2.2 g, 13mmol) portionwise. The reaction mixture is allowed to stir overnight atroom temperature before being quenched with saturated aqueous sodiumthiosulfate (5 mL). Water (15 mL) and diethyl ether (50 mL) are addedand the layers separated. The organic layer is washed with brine (10 mL)and dried over magnesium sulfate. Rotary evaporation yields a crudesolid which is flash chromatographed using 2:1 hexane-ethyl acetatedoped with acetic acid (2 mL per 300 mL of solvent) as eluent. Thedesired 2-trifluoromethyl-3-cyano-4,5-dibromopyrrole (0.8 g, 2.5 mmol,40%) is isolated as a pale yellow solid.

EXAMPLE 14 Preparation of 45-Dibromo-1-Methyl-2-(Fluoromethyl)Pyrrole-3-Carbonitrile ##STR20##

To a solution of the 2-trifluoromethyl-3-cyano-4,5-dibromopyrrole (0.5g, 1.6 mmol) in 30 mL of dry tetrahydrofuran is added potassiumtert-butoxide (0.2 g, 1.9 mmol) portionwise. The rose colored solutionis allowed to stir for 20 minutes before the addition of methyl iodide(0.6 g, 4.2 mmol) neat. The resulting suspension is stirred for 5 hoursbefore being quenched by the addition of 10 mL of water. Diethyl ether(50 mL) is also added and the layers are separated. The organic phase iswashed with brine (10 mL) and dried over magnesium sulfate. Rotaryevaporation yields a crude solid which is flash chromatographed oversilica gel using 4:1 hexane-ethyl acetate as eluent to provide theN-methylated pyrrole (0.4 g, 1.2 mmol, 77%) as a light yellow solid, mp123°-125° C.

EXAMPLE 15 Preparation of 3,4-Dibromo-5-Nitropyrrole-2-Carbonitrile##STR21##

A sample of 5-nitropyrrole-2-carbonitrile (0.4 g, 0.003) is readilysoluble in 10 mL of dilute sodium hydroxide (0.4 g, 0.01 mol). Bromine(0.96 g, 0.006 mol) is added dropwise which results in the deposition ofa solid precipitate. Additional 10% sodium hydroxide is added until allthe solid is dissolved. The solution is then stirred 15 minutes beforeacidifying with dilute hydrochloric acid. The white precipitate iscollected and dried. The product (0.5 g, 56%) has mp 181°-186° C.

EXAMPLE 16 Preparation of 3,5-Dibromo-4-Nitropyrrole-2-Carbonitrile##STR22##

4-Nitropyrrole-2-carbonitrile (0.6 g, 0.0042 mol) is readily soluble in15 mL of water containing sodium hydroxide (0.5 g, 0.012 mol). Bromine(1.34 g, 0.008 mol) is added dropwise, resulting in the formation of asolid precipitate. Sodium hydroxide (10% solution) is then added untilthe solid is dissolved. The resulting solution is stirred for 15 minutesbefore acidifying the solution with dilute hydrochloric acid. The whiteprecipitate (1.0 g, 83%) has mp 170°-175° C.

Calcd. for C₅ HBr₂ N₃ O₂ : C, 20.35; H, 0.33; N, 14.24; Br, 54.20.

Found: C, 20.72; H, 0.23; N, 14.16; Br, 53.50.

EXAMPLE 17 Preparation of 2,4,5-Trichloropyrrole-3-Carbonitrile##STR23##

TO a stirred mixture of 1.50 g (16.3 mmol) of pyrrole-3-carbonitrile in50 mL of glacial acetic acid is added quickly dropwise 4.1 mL (51.0mmol) of sulfuryl chloride by syringe through a rubber septum. With thisaddition the temperature of the reaction mixture rises from about 22° C.to 32° C. The mixture is stirred one and one-half hours and then dilutedwith 100 mL of water. The resulting solids are collected by filtrationand washed with water. On drying, the yield is 2.23 g (70%) of whitesolid, mp>300° C.

EXAMPLE 18 Preparation of 2,4,5-Tribromopyrrole-3-Carbonitrile ##STR24##

To a stirred mixture of 1.50 g (16.3 mmol) of pyrrole-3-carbonitrile in20 mL of chloroform is added dropwise from an addition funnel a mixtureof 2.5 mL (48.5 mmol) of bromine in 7.5 mL of chloroform over about 30minutes. The temperature of the mixture rises to 38° C. and a gummysolid is formed which necessitates addition of additional chloroform (25mL) and some warming to achieve good stirring. The mixture is stirred anadditional 2 hours at room temperature and the solid product iscollected by filtration and washed with chloroform. The collected solidsamount to 4.55 g. Concentration of the filtrate affords another 0.58 gof product. The combined solids are slurried with boiling methylenechloride. On cooling, filtration gives 3.66 g of a pale orange powder,mp 253°-255° C.

Anal. Calcd for C₅ HBr₃ N₂ : C, 18.26; H, 0.31; N, 8.52; Br, 72.91.

Found: C, 18,28; H, 0.35; N, 8.52; Br, 72.74.

EXAMPLE 19 Preparation of 2,4,5-Triiodopyrrole-3-Carbonitrile ##STR25##

4-cyanopyrrole-2-carboxylic acid (1.36 g, 0.01 mol) is added to a warmsuspension of sodium bicarbonate (16.8 g, 0.2 mol) in water (150 mL).After all the acid has dissolved, a solution of iodine (8.3 g, 0.033mol) and potassium iodide (11.0 g, 0.066 mol) in water (50 mL) is slowlyadded with stirring over 1 hour. The mixture is heated at 70°-80° C. for2 hours and cooled in an ice bath and then left in the refrigeratorovernight. The solids are collected, washed well with water and aredried. Flash column chromatography on silica gel packed in methylenechloride and eluted with 3% ethyl acetate in methylene chloride givesthe product as a yellow solid on crystallization from ethyl acetate(0.65 g); mp 257.0°-258.0° C.

EXAMPLE 20 Preparation of 1-Methyl-2,4,5-Trichloropyrrole-3-Carbonitrile##STR26##

To a stirred mixture of 0.70 g (6.2 mmol) of potassium t-butoxide in 25mL of dry THF under a nitrogen atmosphere, is added dropwise from anaddition funnel 1.00 g (5.12 mmol) of2,4,5-trichloropyrrole-3-carbonitrile in 20 mL of dry THF over a 15minute period. After 15 minutes, 0.50 mL (8.03 mmol) of methyl iodide isadded dropwise by syringe over 10 minutes. Solids are formed and afterstirring for about 3 hours, the mixture is diluted with 100 mL of water.The cloudy mixture is extracted twice with ethyl acetate and thecombined organic layers washed successively with dilute NaOH, water, andsaturated salt solution. After drying over magnesium sulfate, theorganic mixture is filtered and concentrated in vacuo to give 0.99 g ofan off-white solid. Purification by chromatography on silica gel usingmethylene chloride affords 0.68 g of yellow-white solid which isslurried with hexane and recovered by filtration; mp 110°-114° C.

Anal. Calcd for C₆ H₃ Cl₃ N₂ : C, 34.40; H, 1.44; N, 13.38; Cl, 50.78.

Found: C, 34,25; H, 1.50; N, 13.36; Cl, 50.88.

EXAMPLE 21 Preparation of 1-Methyl-2,4,5-Tribromopyrrole-3-Carbonitrile##STR27##

To a stirred mixture of 0.87 g (7.75 mmol) of potassium t-butoxide in 30mL of dry THF under a nitrogen atmosphere is added dropwise from anaddition funnel 2.10 g (6.39 mmol) of2,4,5-tribromopyrrole-3-carbonitrile in 20 mL of dry THF. After 15minutes, 0.64 mL (10.3 mmol) of methyl iodide is added by syringe over 2minutes. After several hours at room temperature, the mixture is dilutedwith 100 mL of water and 75 mL of ethyl acetate. The separated waterphase is extracted again with ethyl acetate and the combined organiclayers are washed with dilute sodium hydroxide, water, and saturatedsalt solution. After drying over magnesium sulfate, the mixture isshaken with activated charcoal and filtered. Concentration in vacuogives 1.96 g of white solid; slurrying with hexane reduces this to 1.71g, mp 142°-152° C.

Anal. Calcd for C₆ H₃ Br₃ N₂ : C, 21.02; H, 0.88; N, 8.17; Br, 69.93.

Found: C, 21.12; H, 0.90; N, 8.14; Br, 70.07.

EXAMPLE 22 Preparation of 1-Benzyl-2,4,5-Tribromopyrrole-3-Carbonitrile##STR28##

To a stirred mixture of 1.00 g (3.04 mmol) of2,4,5-tribromopyrrole-3-carbonitrile and 0.68 g (6.1 mmol) of potassiumt-butoxide in 30 mL of dry THF under a nitrogen atmosphere is added 1.10mL of benzyl bromide. The mixture is heated to reflux and stirredovernight. After dilution with 100 mL of water and 150 mL of ethylacetate, the organic mixture is separated and washed with salt solution,dried over magnesium sulfate, and concentrated in vacuo to leave 2.34 gof orange oil. The oil is triturated under a mixture of 5:1 hexane/etherto give a white solid collected by filtration; 0.81 g, mp 100°-103° C.The filtrate yields a second crop; 0.11 g, mp 100°-103° C.

EXAMPLE 23 Preparation of 1-Allyl-2,4,5-Tribromopyrrole-3-Carbonitrile##STR29##

Potassium t-butoxide (0.75 g, 6.7 mmol) is added portionwise at roomtemperature to a solution of 2,4,5-tribromopyrrole-3-carbonitrile (2.0g, 6.1 mmol) in anhydrous tetrafuran (20 mL). After 30 minutes allyliodide (1.12 g, 6.7 mmol) is added dropwise and then refluxed for 2hours. Work-up as described in Example 15 gives the product as a palepink liquid (2.1 g).

EXAMPLE 24 Preparation of Ethyl 2,4,5-Tribromo-3-Cyanopyrrole-1-Acetate##STR30##

Potassium t-butoxide (0.75 g, 6.7 mmol) is added in portions at roomtemperature to a solution of 2,4,5-tribromopyrrole-3-carbonitrile (2.0g, 6.1 mmol) in anhydrous tetrahydrofuran (20 mL). After 30 minutes,ethyl bromoacetate (1.12 g, 6.7 mmol) is added dropwise and the mixturestirred for 4-5 hours at room temperature. Work-up as described inExample 15 gives the product as white solid (0.42 g) mp 140°-143° C.

EXAMPLE 25 Preparation of 2,4,5-Tribromo-1-Ethylpyrrole-3-Carbonitrile##STR31##

Potassium t-butoxide (0.75 g, 6.7 mmol) is added in portions at roomtemperature to a solution of 2,4,5-tribromopyrrole-3-carbonitrile (2.0g, 6.1 mmol) in anhydrous tetrahydrofuran (20 mL). After 30 minutes,ethyl iodide (1.04 g, 6.7 mmol) is added dropwise. The reaction solutionis stirred at room temperature for 30 minutes and then refluxed for 90minutes. The mixture is cooled, diluted with water and extracted withethyl acetate. The organic layer is washed with water and saturatedsodium chloride and dried (Na₂ SO₄). Evaporation of the solvent andcrystallization from ether-hexanes gives a solid which is furtherpurified by flash column chromatography on silica gel, packed withmethylene chloride and eluted with 3% ethyl acetate in methylenechloride. The analytically pure sample is finally crystallized frommethylene chloride-hexanes as a white solid (1.5 g); mp 108.5°-109.5° C.

EXAMPLE 26 Preparation of 2,4,5-Tribromo-1-Ethlylpyrrole-3-Carbonitrile

in the same manner described for the preparation of2,4,5-tribromo-1-ethylpyrrole-3-carbonitrile in Example 23, using therequisite cyanotrihalopyrrole and appropriate alkylating agent, theadditional analogs illustrated below are prepared: ##STR32##

EXAMPLE 27 Preparation of 2,4,5-Tribromopyrrole-1,3-Dicarbonitrile##STR33##

Potassium t-butoxide (614 mg, 5.74 mmol) is added in portions at roomtemperature to a solution of 2,4,5-tribromopyrrole-3-carbonitrile (1.50g, 4.56 mmol) in anhydrous tetrahydrofuran (20 mL). After 15 minutes asolution of cyanogen bromide (177 mg, 5.74 mmol) in tetrahydrofuran (5mL) is added dropwise. The reaction solution is stirred at roomtemperature overnight as it turns cloudy. The mixture is diluted withwater and extracted with ethyl acetate. The organic layer is washed withwater and saturated sodium chloride and dried over (Na₂ SO₄).Evaporation of the solvent and crystallization of the residue from ethergives a white solid (1.20 g); mp 195.0°-197.5° C.

EXAMPLE 28 Preparation of 3,4,5-Tribromopyrrole-2-Carbonitrile ##STR34##

Sodium hydroxide (3.2 g, 0.08 mol) is dissolved in 100 mL of waterfollowed by the addition of pyrrole-2-carbonitrile (2.6 g, 0.027 mol). Afew mL of dioxane is added to make the mixture homogenous. Then bromine(12.96 g, 0.081 mol) is added in small portions at 28°-35° C. withperiodic cooling. Before the addition is complete, solids begin toprecipitate. Everything is brought back into solution by the addition of10% sodium hydroxide. Then the remaining bromine is added and thesolution stirred for 15 minutes before acidifying with dilutehydrochloric acid. The white solid (7.4 g, 84%) is collected and, afterdrying, has mp 215°-218° C.

Calcd for C₅ HN₂ Br₃ : C, 18.25; H, 0.30; N, 8.51; Br, 72.92.

Found: C, 18.06; H, 0.37; N, 8.39; Brt 72.72.

EXAMPLE 29 Preparation of 3,4,5-Tribromo-1-Methyl-Pyrrole-2-Carbonitrile##STR35##

3,4,5-Tribromo-pyrrole-2-carbonitrile (1.0 g, 0.003 mol) is dissolved ina mixture of acetone (20 mL) and dimethoxyethane (10 mL). potassiumcarbonate (0.45 g, 0.0033 mol) is added followed by methyl iodide (0.478g, 0.0033 mol). After stirring overnight at room temperature, themixture is poured into water precipitating a white solid. The solid (0.8g, 80%) has mp 115°-119° C.

Calcd for C₆ H₃ Br₃ N₂ : C, 21.00; H, 0.87; N, 8.17; Br, 69.94.

Found: C, 20.98; H, 0.94; N, 8.05; Br, 69.55.

EXAMPLE 30 Preparation of 3,5-Dibromo-Pyrrole-2,4-Dicarbonitrile##STR36##

Pyrrole-2,4-dicarbonitrile (0,5 g, 0.004 mol) is readily soluble in 15mL of water containing sodium hydroxide (0.5 g, 0.012 mol). Bromine(1.34 g, 0.008 mol) is then added and the solution stirred for 15minutes. Thin layer chromatography (90/10 methylenechloride/acetonitrile) indicates the reaction is incomplete. Additionalbromine is added and the reaction monitored by Tlc. When the reaction iscomplete, the mixture is acidified and a white solid collected. Thesolid (0.47 g, 40.8%) after recrystallization from dichloroethane (30mL) has mp 227°-232° C.

Calcd for C₆ HBr₂ N₃ : C, 26.20; H, 0.36; N, 15.28; Br, 58.15.

Found: C, 26.25; H, 0.58; N, 15.17; Br, 58.35.

EXAMPLE 31 Preparation of 3,5-Dibromo-1-Methylpyrrole-2,4-Dicarbonitrile##STR37##

A sample (1.0 g, 0.0036 mol) of 3,5-dibromopyrrole-2,4-dicarbonitrile isreadily soluble in 20 mL of acetone. Anhydrous potassium carbonate (0.64g, 0.0046 mol) is added, and while the slurry is stirred, methyl iodide(0.68 g, 0.0047 mol) is added. The reaction can be followed by Tlc. Whenthe reaction is complete, the mixture is poured into water precipitatinga white solid. The product (0.77 g, 74%) has mp 175°-178° C.

Calcd for C₇ H₃ Br₂ N₃ : C, 29.08; H, 1.04; N, 14.54; Br, 55.33.

Found: C, 29.09; H, 1.42; N, 14.48; Br, 54.95.

EXAMPLE 32 Preparation of 3-Bromo-2,5-Dichloro-4-Nitropyrrole ##STR38##

The title compound can be prepared by dissolving a sample of2,5-dichloro-3-nitropyrrole (0.54 g, 0.003 mol) in 10 mL of dilutesodium hydroxide (0.25, 0.006), and adding bromine (0.48 g, 0.003 mol).If solid precipitates before all the bromine is added, additional basecan be added. When the addition is complete, the solution can beacidified with dilute hydrochloric acid to precipitate the desiredproduct.

EXAMPLE 33 Preparation of 4-(Trifluoromethlyl)pyrrole-3-Carbonitrile##STR39##

A mixture of p-tolylsulfonylmethylisocyanide (0.72 g, 3.2 mmol) andsodium hydride (0.09 g, 3.8 mmol) in anhydrous ethyl ether is treateddropwise with a solution of 4,4,4-trifluorocrotonitrile (0,38 g, 3.2mmol) in ether and dimethyl sulfoxide over a 35 minute period, stirredat room temperature for 20 minutes and quenched with water. The phasesare separated and the aqueous phase is extracted with ether. The organicphases are combined, washed with brine, dried over MgSO₄ andconcentrated in vacuo to afford an orange solid residue. The residue isflash chromatographed using silica gel and 100:100:1 petroleum ether:ethyl ether: acetic acid followed by 100% methylene chloride to give thetitle product as a white solid, mp 96° to 97° C.

EXAMPLE 34 Preparation of2,5-Dibromo-4-(Trifluoromethyl)Pyrrole-3-Carbonitrile ##STR40##

A mixture of 4-(trifluoromethyl)pyrrole-3-carbonitrile (0.10 g, 0.63mmol) and sodium acetate (0.2 g, 2.4 mmol) in acetic acid is treateddropwise with a solution of bromine (0.23 g, 1.4 mmol) in acetic acid,stirred for 6 hours at 25° C. and poured into an aqueous metabisulfitesolution. The resultant mixture is filtered and the filter cake iswashed with water and air-dried to yield the title compound as a whitesolid, 0.11 g (58%), mp 198° to 200° C.

EXAMPLE 35 Preparation of2,5-Dibromo-1-Methyl-4-(Trifluoromethyl)Pyrrole-3-Carbonitrile ##STR41##

A solution of 2,5-dibromo-4-(trifluoromethyl)pyrrole-3-carbonitrile(0.10 g, 0.30 mmol) in tetrahydrofuran is treated with solid potassiumt-butoxide (0.053 g, 0.49 mmol), stirred for 1 hour at 25° C., treateddropwise with methyl iodide (0.067 g, 0.47 mmol), stirred for 2 hours at25° C. and for 1 hour at 50° C. and diluted with water and ether. Thephases are separated and the organic phase is washed sequentially withwater and brine, dried over MgSO₄ and concentrated in vacuo to affordthe title compound as a white solid, 0.09 g, mp 101° to 104° C.

EXAMPLE 36 Preparation of 4,5-Dibromo-1-Methylpyrrole-2-Carbonitrile##STR42##

A solution of 1-methylpyrrole-2-carbonitrile (1.06 g, 0.01 mol) intetrahydrofuran is treated with N-bromosuccinimide (5.34 g, 0.03 mol) at25° to 30° C., stirred for 18 hours at 25° C. and concentrated in vacuoto give a residue. The residue is taken up in carbon tetrachloridefiltered and the filtrate is concentrated in vacuo to give a solidresidue. Recrystallization from ethanol/water yields the title productas a grey solid, mp 104° to 105° C.

EXAMPLE 37 Preparation of Ethyl 4-(Trifluoromethyl)pyrrole-3-Carboxylate##STR43##

A solution of potassium t-butoxide (8.11 g, 0.075 mol) intetrahydrofuran at -60° C. is treated dropwise with a mixture of ethyl4,4,4-trifluorocrotonate (10.5 g, 0.063 mol) andp-tolylsulfonylmethylisocyanide (12.2 g, 0.063 mol) in tetrahydrofuranover a 1 hour period, stirred at -60° C. for 30 minutes, allowed to warmto room temperature and quenched with water. The reaction mixture isextracted with ether and ethyl acetate. The combined extracts are washedwith brine, dried (MgSO₄) and concentrated in vacuo to give a solidresidue. Recrystallization from 1,2-dichloroethane affords the titlecompound as a tan solid, 7.3 g (56%), mp 163° to 164° C.

EXAMPLE 38 Preparation of Ethyl1-Methyl-4-(Trifluoromethyl)-Pyrrole-3-Carboxylate ##STR44##

A solution of potassium t-butoxide (4.5 g, 0.04 mol) in tetrahydrofuranis treated dropwise with a solution of ethyl4-(trifluoromethyl)pyrrole-3-carboxylate (8.3 g, 0.04 mol) intetrahydrofuran over a 20 minute period at 20°-25° C., stirred for 30minutes, treated dropwise with methyl iodide (5.7 g, 0.04 mol), stirredat room temperature for 24 hours and poured into water. The resultantmixture is extracted with ether and the combined extracts are washedwith brine, dried (MgSO₄) and concentrated in vacuo to afford a brownoil residue. The residue is distilled using a Kugelrohr distillationapparatus to give a gummy solid at 80° to 85° C./0.2 mm Hg. The solid ispurified using ether and basic alumina to yield the title compound as aclear oil, 6.37 g (72%), identified by NMR and elemental analyses.

EXAMPLE 39 Preparation of1-Methyl-4-(Trifluoromethlyl)Pyrrole-3-Carboxylic Acid ##STR45##

A mixture of ethyl 1-methyl-4-(trifluoromethyl)pyrrole-3-carboxylate(4.4 g, 0.02 mol) and 4N sodium hydroxide (5 ml, 00.02 mol) in ethanolis stirred for 24 hours at room temperature, diluted with water andextracted with ether. The aqueous phase is acidified with 10% HCl andfiltered. The filter cake is washed with water and dried in vacuo at 45°C. to afford the title compound as an off-white solid, 2.4 g (62%), mp210° to 212° C.

EXAMPLE 40 Preparation of1-Methyl-4-(Trifluoromethyl)Pyrrole-3-Carbonitrile ##STR46##

A mixture of 1-methyl-4-(trifluoromethyl)-pyrrole-3-carboxylic acid(1.93 g, 0.01 mol) in acetonitrile at 40°-45° C. is treated dropwisewith chlorosulfonylisocyanate (1.41 g, 0.01 mol), heated at 40° C. for24 hours, cooled to room temperature, treated with dimethylformamide(1.46 g, 0.02 mol), heated at 40° C. for 8 hours, cooled to roomtemperature, stirred for 48 hours at room temperature and poured intowater. The resultant mixture is extracted with ethyl acetate. Theextracts are combined, washed sequentially with water and brine, dried(MgSO₄) and concentrated in vacuo to afford an oily solid residue. Theresidue is taken up in ethyl acetate, washed with 1% aqueous sodiumhydroxide, dried (MgSO₄) and concentrated in vacuo to give a yellow oilresidue. Kugelrohr distillation at 100° to 110° C./2 mm Hg yields thetitle product as a white solid, 0.95 g (54%).

EXAMPLE 41 Preparation of Phenyl2,3,5-Tribromo-4-Cyanopyrrole-1-Carboxylate ##STR47##

A mixture of 7.0 g of 2,4,5-tribromopyrrole-3-carbonitrile and 2.9 g ofpotassium t-butoxide in tetrahydrofuran is treated with 13.8 g of phenylchloroformate, heated at reflux temperature for 12 hours, cooled, pouredinto water and filtered. The solid filter cake is washed with water anddried in vacuo to afford the title compound. A sample is recrystallizedfrom a mixture of ethyl acetate and methylcyclohexane to give colorlesscrystals, mp 128° to 129° C.

EXAMPLE 42 Preparation of Methyl2,3,5-Tribromo-4-Cyanopyrrole-1-Carboxylate ##STR48##

A solution of 2,4,5-tribromopyrrole-3-carbonitrile (3.0 g, 0.091 mol) intetrahydrofuran is treated portionwise with potassium t-butoxide (1.33g, 0.012 mol) at room temperature, stirred for 20 minutes, treateddropwise with a solution of methyl chloroformate (1.29 g, 0.014 mol) intetrahydrofuran, stirred for 21/2 days, poured into water and extractedwith ether. The combined ether extracts are washed with brine, driedover MgSO₄ and concentrated in vacuo to give a brown solid residue. Theresidue is recrystallized from ethyl acetate/hexanes to afford the titlecompound as a tan solid, 1.4 g (39.5%) mp 119.5° to 122.0° C.

Using the above procedure and substituting the appropriatechloroformate, the following compounds are obtained:

    ______________________________________                                         ##STR49##                                                                             R         mp °C.                                              ______________________________________                                                 OCHCH.sub.2                                                                             112-113                                                             OCH.sub.2 CHCH.sub.2                                                                    86-89                                                      ______________________________________                                    

EXAMPLE 43 Preparation of2,4,5-Tribromo-1-(p-Chlorobenzoyl)-Pyrrole-3-Carbonitrile ##STR50##

A mixture of 2,4,5-tribromopyrrole-3-carbonitrile (5.0 g, 0.015 mol) andpotassium t-butoxide (2.0 g, 0.018 mol) in dry tetrahydrofuran isstirred for 10 minutes at room temperature, treated dropwise with asolution of p-chlorobenzoyl chloride (3.25 g, 0.018 mol) intetrahydrofuran, heated at reflux temperature for 3 hours, cooled anddiluted with a mixture of water and ethyl acetate. The organic phase isseparated, washed with brine, dried over Na₂ SO₄ and concentrated invacuo to afford a tan solid residue. Recrystallization from benzenegives the title compound as a cream colored solid, 2.9 g (41.4%), mp154°-157° C.

Using the above procedure and substituting p-methoxybenzoyl chloridegives 2,4,5-tribromo-1-(p-methoxybenzoyl)pyrrole-3-carbonitrile, mp 86°to 89° C.

What is claimed is:
 1. A method for detecting flukicidal activity of acompound comprising the steps of:(a) administering a non-lethal dosageof the compound to an animal; (b) waiting a period of time sufficient toallow the compound to circulate to the animal's liver; (c) dissectingthe animal's liver; (d) administering a portion of the dissected liverto a medium containing a free-living flatworm wherein the portion is ofan amount sufficient for the flatworm to feed upon; (e) observing theflatworm for feeding upon the dissected liver and; (f) observing theflatworm for the presence of mortality or morbidity.
 2. The methodaccording to claim 1, wherein the animal is a gerbil.
 3. The methodaccording to claim 1, wherein the free-living flatworms are fresh-waterplanaria.
 4. The method according to claim 1, wherein the planaria areselected from the group consisting of Dugesia tigrina and Phagocatamorgani.
 5. The method according to claim 1, wherein step (a) isconducted by administering the compound in the animal's diet for aperiod of about four days.
 6. The method according to claim 1, whereinstep (a) is conducted parenterally or by oral gavage.
 7. The methodaccording to claim 6, wherein step (c) is conducted from about two hoursto about twenty-four hours after step (a).
 8. The method according toclaim 1, wherein the medium is sterilized pond water.